1. Field of the Invention
The present invention relates to a gas-inlet attachment for use in charging a gas container with a fresh supply of gas. More particularly, the present invention relates to a gas-inlet attachment for inclusion in the mouthpiece of a gas charger, wherein the gas-inlet attachment includes an air-tightly sealed pressure differentiator allowing the check valve in the cock to open under a differentiated pressure against the charging gas pressure, thereby facilitating the gas charging operation, and also avoiding a leakage problem.
2. Description of the Prior Art
It is the common practise to employ a check valve in a plug-cock type of valve for preventing an outside air containing impurities, such as dust and dirt, from entering the container when it is empty; otherwise, a freshly charged gas is in danger of contamination with the impurities.
However, to supply gas to the container, the check valve must be kept open. To open it, various proposals have been offered, among which is a special attachment for opening the check valve by the charging gas per se, as will be described more fully hereinafter. This prior art attachment has an advantage of dispensing with the necessity of employing any special tool or device for opening the check valve, but it has been found that the advantage is traded off by many disadvantages, such as:
1. It is unavoidable for some portion of the charging gas to leak into the atmosphere. This will be of particular disadvantage when the gas is of toxic or explosive nature;
2. A gas-inlet mouthpiece must be made specially for the mouthpiece. This leads to a high production cost.
3. The attachment tends to be heavy with a relatively large gas-inlet mouthpiece; with such a heavy attachment it is time- and labor-consuming to fix it on the cock with its gas-inlet passage being in alignment with the gas-outlet passage of the cock. In addition, there is a danger of damaging the check valve in the cock.
The aim underlying the present invention essentially resides in providing an improved gas-inlet attachment which can allow the check valve to open by a charging gas without the possibility of leakage problems, and which is readily applicable to ready-made cocks.